This invention relates to closures for containers and more particularly, it relates to closures for containers of dangerous or harmful contents which are of the child-resistant type to deter access to the contents of the container by children. In other words, the closure and container are so constructed that the closure may be easily positioned on the container into a locking position, but in order to remove the closure from the container, some considerable thought and specific intent is necessary. The closure and container neck each have mating threaded portions which facilitate the attachment of the closure to the container neck. The closure also includes one or more locking lugs on its interior surface which engage one or more camming projections on the neck of the container to prevent rotational removal of the closure from the container. The closure may be removed from the container only by squeezing the closure on opposite sides to force the locking lugs radially outwardly beyond the camming projections to permit rotation of the closure relative to the container. The camming projections on the container neck are of sufficient axial height to prevent rotation of the closure relative to the container both when the closure is fully tightened onto the container and when the closure has been rotated 180.degree. relative to the container, thereby necessitating two separate squeezing actions to remove the closure from the container.
The prior art has suggested many types of safety caps and container configurations for keeping poisons, dangerous chemicals and other medications away from children or unsuspecting adults. Examples of such prior art patents which disclose safety caps of the type that are squeezed in order to facilitate removal of the cap from the container include U.S. Pat. Nos. 3,376,991 (Deaver) and 3,830,391 (Uhlig).
The prior art devices of the squeeze-and-turn type have heretofore suffered in the respect that they have been difficult and expensive to manufacture or have required rather substantial changes to the mold for the threaded container neck portion. For example, the abovementioned Deaver patent requires an oval shape for the neck portion of the container, and the Uhlig patent requires flat cutaway portions on the container neck configuration. These modifications in the cited patents are required to provide space for squeezing the closure inwardly to disengage the locking means between the closure and the container neck.
In the safety cap field, it is usually desirable to require a relatively high degree of manual dexterity in removing the cap, but once it is removed, it is desired to replace it as quickly as possible without necessitating complicated maneuvers. It is also desirable to utilize a threaded engagement between the closure and container, as this type of engagement has been found to provide a very tight seal for maintaining the contents, particularly liquids, within the container.